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Cogito, Ergo Sum - An Analysis

I think, therefore I am. A statement which, though coined centuries past, remains perhaps one of, if not the most recognized philosophical statement(s). René Descartes, the esteemed 17th century philosopher and mathematician who is often regarded as the “Father of Modern Philosophy,” first proclaimed this in his book Discourse on the Method [1637] (French: “Discours de la méthode”) originally in French as “Je pense, donc je suis,” and was later on translated in Latin, to the more widely known formulation - “Cogito, ergo sum.”


Je Pense | donc | je suis

Cogito | ergo | sum

I think | therefore | I am

It was only later on where the English translation, “I think, therefore I am” came to be, for Descartes only wrote in either French or Latin.

The phrase “I think, therefore I am” is simply referred to as “the cogito,” in respect to its Latin translation when being discussed by scholars and philosophers. Hence, whenever I am to reference this maxim, I too shall refer to it simply as “the cogito” for convenience's sake.

Despite the cogito’s fame, its origins and actual meaning, unlike the statement which it is associated with, remains rather unknown and obscure to many people. Such is the reason I decided to undertake such an endeavor. For I believe that this dictum does not get the recognition it deserves, given that the impact and influence the philosophical statement itself had, and the method used to arrive at this conclusion (more on that later) had on Western philosophy has been nothing short of great magnitude.

On Skepticism, Methodical Doubt, and Absolute Certainty

To know how Descartes arrived at this conclusion, we must turn to one of his books, Meditations on First Philosophy [1641]. In a series of six meditations, each of which having its own theme, Descartes goes in depth in his philosophical method, thereby discovering the cogito, which would go on to serve as the fundamental basis of all Cartesian* philosophy.

*The adjective “Cartesian,” which refers to anything which is related to or derived from Descartes or his ideas, is actually derived from his Latinized name, “Renatus Cartesius.”


Descartes first and foremost recognizes the challenge that skepticism poses in the field of epistemology, which may be described as “the philosophical study of the nature, origin, and limits of human knowledge” (Stroll & Martinich, 2021). The Branch of epistemology attempts to answer questions such as, “Where does our knowledge come from?”, “How have we come to gain our knowledge?”, “How can we know that our knowledge is perfect?” and so on. Now the skeptics argue that our cognitive faculties are too flawed to allow us to properly discern that which is true from falsehoods (Dicker, 2013), thus implying absolutely nothing can be known for certain. Unsatisfied with this view, Descartes would go on to attempt to answer and refute this claim made by the skeptics.

The author opens the meditation by noting that many of the beliefs and opinions from his youth which he had taken to be true were, in fact, false (as established by skepticism). As a result, he recognizes that the body of knowledge which he possessed was, by virtue of being built upon falsehoods, incredibly faulty. Thus, as a firm seeker of truth and absolute certainty, he set out to establish a firm, reliable intellectual foundation to his knowledge, a foundation based on that which is impossible to doubt, to not just serve as a refutation to the skeptics but to benefit him as well by allowing him to build an entirely new body of knowledge that is established in truth and certainty. This approach is also known as foundationalism, which is a theory described as “the view that all our knowledge begins with some self-evident beliefs, which are not evidenced by any others yet provide our justification for all the rest we know” (Cottingham, 1992).

To achieve this, Descartes took a methodical approach in such a task, which the following excerpt from the Meditations describes well:

“But since reason already persuades me that I should no less scrupulously withhold my assent from what is not fully certain and indubitable than from what is blatantly false, then, in order to reject them all, it will be sufficient to find some reason for doubting each one. Nor shall I therefore have to go through them each individually, which would be an endless task: but since, once the foundations are undermined, the building will collapse of its own accord, I shall straight away attack the very principles that form the basis of all my former beliefs.”

[“Meditations on First Philosophy with Selections from the Objections and Replies”, p. 13]

Descartes decided that he would engage in an intellectual “assault” to his beliefs, by calling into doubt any belief that is, even by the slightest degree, possible to doubt, but he would not stop there. Not only will he cast into doubt everything that may possibly be doubted, but he will treat everything that may in the slightest degree be doubted as if it were false. In doing this, he seeks to “clear out the rubble” and start anew with a set of beliefs consisting of that which can be known with absolute certainty. Such a process has come to be known as methodic doubt.

However, he will endeavor not to find reason to doubt every single one of his opinions and beliefs, for that might very well be an endless task. Rather, he will look to find reason to doubt the most fundamental foundations by which his beliefs are based upon. He compares it to that of a building, which collapses entirely purely by undermining its foundations.

Descartes tackles it by recognizing that our senses play a vital role in our beliefs. The author states that the things we learn through our senses, more often than not, shape what we perceive and hold to be true. Be that as it may, Descartes realizes that our senses may at times be deceptive. He acknowledges that our senses in general are reliable, but there have oftentimes been instances of it being misleading (which I am sure most of us can agree with). Applying his radical approach to doubt, he states that our senses may not be trusted, for it would not be wise to put one’s full trust on something that has once deceived you.

Following that train of thought, he stumbles upon yet another observation, this time, in relation to the reality of dreams. Descartes acknowledges the reality of false perceptions when we are in a state of dreaming in our sleep. When we dream, it often feels too real, so real that usually we are not even aware that we are dreaming at all. He states there are no good rock solid methods of indication to definitely distinguish if we are sleeping or not. Thus, applying his methodic doubt yet again, Descartes begins to doubt whether or not we are in fact awake and not just dreaming. Just think about it. How do we know for certain that all of this is true? What if all this (pertaining to the reality we perceive) is merely an illusion brought about by our senses deceiving us yet again? What if all this exists merely in one’s dream? I mean, who is to say with utmost certainty that it isn’t the case? How can one possibly prove, without an iota of doubt, that it isn’t so?

More doubts, particularly as it relates to God (as he was a devout Catholic) and His nature, soon filled his mind. He questions whether or not God actually created a physical universe, or if he has created him to be in a constant state of dreaming or illusion, sort of like existing within a simulation, if you will. However, reconciling this thought with the very nature of God was (to him) impossible. Conceiving God, who is supposed to be the ultimate paradigm of goodness and the wellspring truth as a deciever was a contradiction as it stood. Thus, the author reformulates, and proceeds to articulate a well-known concept of his, that being his evil demon (or evil spirit/evil deceiver depending on the version’s translation) as such -

“I will therefore suppose that, not God, who is perfectly good and the source of truth, but some evil spirit, supremely powerful and cunning, has devoted all his efforts to deceiving me. I will think that the sky, the air, the earth, colours, shapes, sounds, and all external things are no different from the illusions of our dreams, and that they are traps he has laid for my credulity; I will consider myself as having no hands, no eyes, no flesh, no blood, and no senses, but yet as falsely believing that I have all these;* I will obstinately cling to these thoughts, and in this way, if indeed it is not in my power to discover any truth, yet certainly to the best of my ability and determination I will take care not to give my assent to anything false, or to allow this deceiver, however powerful and cunning he may be, to impose upon me in any way.”

[“Meditations on First Philosophy with Selections from the Objections and Replies”, pp. 16-17]

Though Descartes did not actually believe the case of the evil deceiver was actually true, he had no definite way of disproving that it was not the case. Thus, he proceeded with his idea. Using the evil demon who employs all his power to deceive him as a basis for doubting the external world, he then concludes that he has no hands, no eyes, that there is no earth, or sky, or water, and that his memories are mere fabrications. He even called into doubt mathematical truths, stating that a deciever great enough could make it possible for him to be “deceived whenever I add two and three, or count the sides of a square, or make a judgment about something even simpler, if anything simpler can be imagined?” How does he know that he is not actually being deceived whenever he counts? For a deceiver, if powerful enough, may even cause him to go astray whenever he were to do this.

Employing his hyperbolic approach to doubt, he denies the reality of the external world, and treats it all as an illusion within a dream. Such a task proved to be incredibly laborious for him, and here he ends the first of his meditations.


Descartes opens his second meditation with a statement that reflects the rather depressing state at which he was in at the time of writing -

“Yesterday’s meditation has plunged me into so many doubts that I still cannot put them out of my mind, nor, on the other hand, can I see any way to resolve them; but, as if I had suddenly slipped into a deep whirlpool, I am in such difficulties that I can neither touch bottom with my foot nor swim back to the surface.”

[“Meditations on First Philosophy with Selections from the Objections and Replies”, p. 17]

Nonetheless, he carried on with his rather hyperbolic method, determined to reach his goal of uncovering that which is beyond any sliver of a doubt, lest he were to fail and come to the undesirable revelation that nothing at all can be known for certain, which would leave him (and I’m sure anyone else) disillusioned, unable to escape miserable chasm of existential uncertainty, so he voluntarily threw himself in.

Carrying on from where he had left, Descartes denies the validity of his means of perception, stating that he has no senses and denying the legitimacy of his memories. Thus, he too rejects the existence of everything that is perceived by these means. There are no shapes, there is no motion, no material objects whatsoever, and so forth, stating that they were mere deceptions conjured up within one’s mind. From these conclusions, what would logically follow, to which Descartes affirmed, was that he had no physical body.

And it is at this point, where he asks himself -

“​​But am I at least not something, after all? But I have already denied that I have any senses or any body. Now I am at a loss, because what follows from this? Am I so bound up with my body and senses that I cannot exist without them? But I convinced myself that there was nothing at all in the world, no sky, no earth, no minds, no bodies. Did I therefore not also convince myself that I did not exist either?”

[“Meditations on First Philosophy with Selections from the Objections and Replies”, p. 18]

Now that I have denied the existence of my body, of my senses, of my memories, and of the world around me, would it then follow, would that possibly mean, that I too do not exist?

No. That cannot be. “I must exist”, the author expresses. For even if there was an evil, all-powerful deceiver (as conceptualised in the first meditation), who has tricked me into believing that there was a world at all, or that I had a body, or that I had any senses, there still has to be someone, a “me” to be deceived. I may be fed the most egregious of lies and untruths, and be persuaded to hold them as what is true, but even then, does that not still require someone, a “me” to be persuaded? And how can one deny their own existence if that task requires someone, a “me” to carry out the denial?

Thus, Descartes concludes that every time he thinks, which, given the illustration of the evil deceiver, would mean that he is also being deceived at that very specific point in time; and as stated previously, if one was in fact being deceived, then that would mean he does in fact exist. However, with all that being said, is it possible for one to doubt that they think? And as one might recall, in Descartes’ method, if something is subject to even the slightest amount of doubt, then it will be treated as entirely false. If it is even minutely possible to doubt what one thinks, then it is in this specific method, entirely false.

Once again, no. One cannot doubt that they think. By virtue of doubting, one already thinks, for the very act of doubting is a type of thinking. Hence, to doubt that one is thinking, is to think that they are not thinking, a statement which contradicts itself, thus proving it false.

Finally triumphant, Descartes proclaims -

“But there is some deceiver or other, very powerful and very cunning, who ever employs his ingenuity in deceiving me. Then without doubt I exist also if he deceives me, and let him deceive me as much as he will, he can never cause me to be nothing so long as I think that I am something. So that after having reflected well and carefully examined all things, we must come to the definite conclusion that this proposition: I am, I exist, is necessarily true each time that I pronounce it, or that I mentally conceive it.”

[“Meditations on First Philosophy with Selections from the Objections and Replies”, p. 18]

So long as he is doubting (or thinking), he is; his thinking already serves as proof of his existence whether or not what he thinks is true. Perhaps he exists not as an actual man, perhaps he exists not in the form of a human, born flesh and blood as he has always thought himself to be. But he nonetheless, still is an existent being.

And so, after all the doubts, woes, and existential crises, Descartes emerges successful. He was finally able to find that one thing, which to him is indubitable, too self-evident to conjure even the slightest amount of doubt against to serve as the foundation for all his knowledge - which was that he exists. And here, though not articulated in this particular formulation in the Meditations, emerges “Je pense, donc je suis”, “Cogito, ergo sum”, “I think, therefore I am”.

On the Matter of Cogitatio

Now that we are (hopefully) acquainted with the cogito and its origins, one rather interesting question may arise in the minds of some. Could we perhaps substitute the statement “I think” with something else to prove our existence? And if so, what would the nature of that statement be? This question has been raised to Descartes himself in the Objections and Replies, which, by the name would suggest, is a written account of Descartes answering several objections raised to his Meditations; sort of like a debate documented on paper. Now Pierre Gassendi, one of Descartes’ critics, stated that Descartes could have just used any other action to prove his existence, for anything that carries out an act must surely exist (Dicker, p. 42).

Now regardless of whether or not this is an actual objection, answering this question will introduce us to an important concept which will aid in providing certainty in the cogito. Now while it may be true that an act needs to be carried out by an actor, and an actor must surely exist, for what else will carry out the act if not for the actor, we must remember where Descartes’ hyperbolic doubting has led us. In the process of such doubting, we have denied the existence of our physical body, and all that remains is the certainty of our thoughts. Thus, we cannot say that “I walk, therefore I exist” or “I eat, therefore I exist” or “I watch, therefore I exist” and so forth, for we have established that the body parts necessary for the fulfilment of these actions, such as our legs, mouth, teeth, eyes, and so forth are falsities, illusions, and cannot serve as proof of our existence.

So, does that mean no other statement can replace the “I think” in the cogito? By no means. Here, we are introduced to the concept of the cogitatio or cogitationes, which is Latin for “thought” and “thoughts” respectively (Dicker, p. 44). When one says that a statement is formulated “in terms of cogitatio,” it simply means that that particular statement is referring to one’s present thinking, or, in a general sense, one’s mental state. This would mean that any statement that refers to any type of thinking, such as doubt (which is what the cogito uses), but also understanding, denying, imagining, and so forth, falls under this description (Newman, 2019.). Now Descartes believed that one can substitute any “cogitatio-statement” into the cogito, and it will still lead to the proof of one’s existence. Statements such as “I imagine, therefore I am” or “I deny, therefore I am” or “I judge, therefore I am” is certainly acceptable for Descartes, for imagining, denying, and judging are acts of thinking, hence cogitatio-statements.

On Questions Regarding the Statement’s Translation

The cogito has sparked vast amounts of literature in the field of philosophy, and has been central to many scholarly dialogues and debates that continue until the present. Now, with the rather dramatic method by which Descartes had used to arrive upon the cogito, and the purpose of engaging in this intellectual endeavour made clear, it would now be a good opportunity to touch on to some of the interesting questions and discussions that have centred around the statement.

Let us begin with the matter of the statement’s translation. As shown in the very beginning of this piece, this statement has first been penned in French as “Je pense, donc je suis,” and later on in Latin, as “Cogito, ergo sum.”

Je Pense | donc | je suis

Cogito | ergo | sum

I think | therefore | I am

What fascinated me while reading commentaries on the cogito, however, was how different sources would refer to the cogito not in its most recognizable formulation, “I think, therefore I am (or exist),” but rather as “I am thinking, therefore I am (or exist).” Such is the case in the book The Cambridge Companion to Descartes edited by John Cottingham (which is an excellent read if one so wishes to study Descartes). Philosopher Peter Markie, a contributor to the aforementioned book who wrote the entry on the cogito (see Chapter 5), would often use “I am thinking, therefore I am” instead of the usual way of phrasing it. John Cottingham himself also prefers using the alternative formulation when citing this maxim.

“So what? It seems quite irrelevant doesn’t it?” one may ask. It may seem so at first. However, in philosophy, the manner in which an argument or proposition is articulated is of utmost importance, for it can drastically affect a statement's validity or soundness, how one approaches the interpretation of the statement, and so forth. In the case of the cogito, the commentators’ use of the progressive tense “thinking” in place of the simple present tense “think,” is a temporal matter; it is meant to implicate when one’s state of existence (which is what the cogito is about) may be proven to be true.

In his book Descartes: An Analytical and Historical Introduction (another great book of commentary on Descartes), Georges Dicker expresses his agreement with John Cottingham’s stance that the present progressive tense is a far better translation of the thought rather than the simple present tense. Dicker quotes Sir Cottingham on the matter.

“[T]he correct English translation of cogito/je pense, when these words occur in Descartes’ discussion of the certainty of his existence, should employ the so-called continuous present—‘I am thinking’—rather than the simple present, ‘I think.’ For what makes me certain of my existence is not some static or timeless fact about me—that I am one who thinks; rather, it is the fact that I am at this moment engaged in thinking. And so long as I continue to be so engaged, my existence is guaranteed.”

[Descartes: An Analytical and Historical Introduction, p. 41]

So, what does this all mean? When one uses the simple present tense, “I think, therefore I am,” it comes with the implication that there is a timeless aspect to this thought as though the truth of this claim is constant regardless of time, circumstance, and whatnot. However, many argue that the cogito is most likely not meant to be interpreted in such a manner. Why so? Well, if one were to take the cogito as a timeless inference, in order to reach the deductive conclusion that one exists, one has to accept the timeless proposition that he or she is a being that thinks (and the simple present formulation, that is ‘thinks’, is of utmost importance). But one must keep in mind at all times when discussing the cogito the radical doubt Descartes employed. Remember, in Descartes' method, he characterised all of his memories as unreliable, as he established that it is possible that there is an evil deceiver out there that is tricking him into remembering things that could very well be false (and even if there is a slight possibility that it is the case, then he treats it as false). Thus, him thinking that he was thinking at any point in the past could have very well been a deception, and so the timeless proposition that he is a being that thinks cannot be reliably used to prove his existence. The only way he can truly be convinced that he is thinking without being deceived is when he is engaged in the act of thinking at the very moment,“For what makes me certain of my existence is not some static or timeless fact about me—that I am one who thinks; rather, it is the fact that I am at this moment engaged in thinking. And so long as I continue to be so engaged, my existence is guaranteed.” as Cottingham once eloquently states (Dicker, 2013). Thus, the truth of the cogito, the certainty of his existence, can only be guaranteed while in the very act of thinking itself, for that is the only time when you know without doubt and not the tenseless, timeless idea that he is a being which thinks, which is why many have been convinced that the more proper translation of Cogito, ergo sum is not I think, therefore I am, but rather, I am thinking, therefore I am (or I exist).

Final Comments

Here ends our discussion on the cogito. Though there still remains an entire library full of questions and topics we may discuss about it, I see it best that we end it here, for this article has touched on (what is to me) the most important aspects of this statement, such as its origins, conditions of its truth, translation, and possible interpretations. Perhaps the one other thing I have not discussed in this article would be certain objections to the cogito by other philosophers and theologians; if one is interested in learning about these objections, I would highly recommend some of the books I have used as reference for this piece, such as The Cambridge Companion to Descartes edited by John Cottingham and Descartes: An Analytical and Historical Introduction by Georges Dicker, but there are plenty articles readily available on the internet that touch on the subject as well.

Philosophising can no doubt can be quite the laborious task (to say the least), with all the little pedantic disputes overly concerned with the use of proper language or all the different concepts that may be confusing to one who is not used to thinking in such abstract terms, but I believe that engaging in such a task can truly be of benefit to anyone by making us more effective critical thinkers. My hope is that all of you have learned something of value from this read, and have found a new appreciation for this iconic aphorism.



Comesaña, J., & Klein, P. (2019, December 5). Skepticism. Stanford Encyclopedia of Philosophy. Retrieved June 9, 2022, from

Cottingham, J. (1992). The Cambridge companion to Descartes. Cambridge University Press.

Descartes, R. (1998). Discourse on method and meditations on first philosophy. Hackett Publishing Co.

Descartes, R. (2008). Meditations on first philosophy: With selections from the objections and replies. Oxford University Press.

Dicker, G. (2013). Descartes: An analytical and historical introduction. Oxford University Press.

Dika, T. R. (2020). Descartes’ method. Stanford Encyclopedia of Philosophy. Retrieved June 28, 2022, from

Newman, L. (2019). Descartes’ epistemology. Stanford Encyclopedia of Philosophy. Retrieved May 18, 2022.

Other References:

Stroll, A., & Martinich, A.P. (2021, February 11). epistemology. Encyclopedia Britannica.

Russell, B. (1912). The problems of philosophy. Oxford University Press.

Special Thanks to

Alex O’Connor (CosmicSkeptic) and his video - Descartes’ Most Famous Idea | Explained, which inspired me to undergo this endeavour and provided me with ideas on what to search up on

O’Connor, A. [CosmicSkeptic]. (2022, January 5). Descartes’ most famous idea | Explained [Video]. YouTube.

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